Calculation of narrow-band spectra by direct decimation

The calculation of the spectrum of a narrow-band signal which is embedded in a broad-band sequence usually requites substantial computation and storage if executed by performing an FFT or DFT's directly on the broad-band sequence. In this paper a new scheme using direct decimation is proposed which computes the narrow-band spectrum with good resolution while requiring only modest computation and storage. The performance of the proposed scheme is analyzed. Examples are presented which demonstrate the efficiency of this scheme when compared with the FFT, DFT, zoom transform, and complex modulation scheme.